Apparatus for sterilizing soil



Aug. 13,1946. B. B. ELL IOTT Re 22,778

v APPARATUS FOR STERILIZING SOIL Original Filed July 4, 19:59 5sheets-sheet 1 74 INVENTOR.

- Buxz 5 ELL/Orr Augul3, 1946. B, B. ELLIOTT APPARATUS FOR STERILIZINGSOIL Original Filed July 4, 19:59 Sheets-Sheet 2 INVENTOR. BQRHQ. B.ELLIOTT :477046VEYJ Aug. 13, 1946. B. B. ELLIOTT I APPARATUS FORSTERILIZING SOIL Original Filed July'4, 1939 3 Sheets-Sheet 3 INVENTORBUR/2. B. ELLIOTT Reissued Aug. 13, 1946 p APPARATUS FOR STERILIZINGSOIL Burr B. Elliott, Seattle, Wash., assignor to Isaacson Iron Works,Seattle, Wash., a corporation of Washington Original N0.2,272,190,.dated February 10, 1942,

Serial No. 282,825,

July 4, 1939. Application for reissue March 26, 1946, Serial No. 657,120

This invention relates to means for the steri- I the soil and the meansprovided for controlling v its expansion and discharge into the soil.

The idea of injecting saturated steam into the soil as a means ofkilling or destroying weed seeds, insect eggs, larvae and pests ingeneral is quite old and various types of devices have been employed forthis purpose, while the use of superheated steam for the same purpose isnot known. In my prior application, filed July 6, 1937, under Serial No.152,193, I have disclosed a means for generating steam and for injectingit into the soil, and while a means provided in accordance with thedisclosures in that application, applied the steam to the soil in asatisfactory manner, it was not as effective from the standpoint ofdestroying the pests as had been anticipated because of loss of heatfrom the steam incident to injection, and hence the present applicationhas been made, which discloses an improved means that overcomes thedeficiencies of the former device, particularly insofar as preventingloss of heat from the steam incident to injection into the ground isconcerned.

Explanatory to the present invention, it will be here stated that inapparatus of the prior art utilizing steam to destroy weed seeds,insects, eggs and the like, the results have not been entirelysatisfactory, mainly because of the absence of or the loss of heat fromthe steam incident to its being injected into the soil. This isaccounted for by reason of the fact that it has generally been the usualpractice to inject saturated steam under pressure into the soil and toliberate it through restricted orifices in the pipes of a distributingsystem. Consequently, as soon as the steam issues from the restrictedorifices, it expands rapidly, blowing the loose soil back away from thesteam. Due to this quick expansion, the steam loses its heat and becomesuseless for its intended purpose before contact with the things it isintended to destroy.

' Most garden and field soils comprise many small interstices which makeup about one-third of the soil volume. These interstices contain airfrom which the seeds and insects of the soil receive their necessarylife sustaining oxygen. A touch of the latent heat carried by steam isdestructive to these potential pests and it is the purpose of thepresent invention to provide means for the application of steam to thesoil in such manner that it will not lose its latent 3 Claims. (01.111- 1) 2 heat, prior to displacing the air and filling all theseinterstices, or before coming in intimate contact with the seeds, eggsand insects, and the like, which it is desirable to destroy.

Therefore, it is the principal object of this invention to provide animproved means for generating steam and. forbringing it to a superheatedcondition and for then applying this steam to the ground withoutmaterial loss of heat prior to its displacing the air from theinterstices of the soil and contacting the things it is desired todestroy.

More specifically stated, the principal object of this invention residesin the method of and in the features or construction of the means forthe applying of steam to the ground for killing Weed seeds, insects,eggs, and the like, in a practical and economical manner.

, Other objects of the invention reside in the details of constructionand combination of parts embodying the apparatus, and in their mode ofoperation for the control and injection of superheated steam into theground, as will hereinafter be fully described.

In accomplishing these and other objects of the invention, I haveprovided the improved details of construction, the preferred forms ofwhich are illustrated in the accompanying drawings, wherein- Fig. l is adiagrammatic plan view of the units employed in the present equipment asused in connection with a tractor for drawing them entrain across afield.

Fig, 2 is an elevation of the steam generating boiler, a part thereofbeing broken away for better illustration of the internal structure.

Fig. 3 is a top, or plan view of the ground furrowing implement andsteam injector piping system embodied in the present invention.

Fig. 4 is a vertical section on the line 4-4 in Fig. 3, illustrating thecharacter and relationship of one of the steam'discharge pipes to aground turning disk.

Fig. 5 illustrates an alternative location of the steam pipes extendingfrom the supply headers to the ground.

Fig. 6 is a sectional view on the line 6-6 in Fig. 5. s

Referring more in detail to the drawings In Fig. 1, It designates, ingeneral, the steam generating and superheating unit; ll designates theground furrowing implement, and piping system for injection of the steaminto the ground,

and I2 designates a tractor or the like, whereby beams and braces I60.

ing implement are drawn entrain. The tractor l2 has here been shown asbeing of the crawler type, and the steam generating unit has beenillustrated as comprising a horizontal frame structure l3, supported byfour ground wheels [4 and connected to the tractor by a draw barstructure I 5, while the ground furrowing implement has been illustratedas comprising a frame structure I5, mounting therein two sets or gangsof plow disks I! and I8, and the frame has been illustrated as equippedwith a draw bar l9, which is attached pivotally to the rear of the frameof the steam generating unit so that the parts are drawn entrain by thetractor.

First describing the steam generating unit In: This comprises the framestructure I3 supported in conventional manner by the ground wheels I4.Mounted upon the frame is a vertical boiler, designated in its entiretyby numeral 25. This boiler may be of conventional design comprising afire-box portion 26, above which is the boiler portion proper 21',equipped with a water injector system, here indicated at 28, and formedwith a steam dome 29. Located in the boiler, just above the fire-box 26,are superheater coils 30, and above these the boiler is equipped withthe vertical tubes 3| as is usual practice.

Leading laterally from the steam dome 29 is a steam delivery pipe 32,equipped with a hand valve 33 for controlling the outlet of steam. Thepipe 32 connects at its outer end to a pipe 34 of like size, leadingdownwardly and then laterally to deliver the steam into the superheatingcoils 30. The superheating coils, being located adjacent to or formingthe sides of the fire-box, receive the steam from pipe 34, and it istherein raised to superheated condition. A pipe 35 leads from thesuperheater coils 30 rearwardly to conduct the steam to the groundworking implement for distribution and injection into the ground; itbeing understood that the flow of steam is in accordance with itsadmittance to pipe 32 by adjustment of valve 33.

In its present preferred form, the ground working implement, designatedin its entirety by numeral ll, comprises a frame structure I6, which, asshown best in Fig. 3, comprises two rectangular sections Ilia and Nib,disposed respectively at front and rear of the frame and joined rigidlytogether in angular relationship by connecting The section IBa, at thefront end of the structure, mounts therein a gang of axially aligneddisk plows l1, evenly spaced on a shaft 40, which is supported at itsends from said frame section. The plow disks [1, in this instance, havehub members l'l', that revolve directly on the supporting shaft.

The rear frame section lBb likewise mounts a gang of disk plows I8,revoluble on a supporting shaft 4|; the disks having mounting hubs thatrevolve directly on the supporting shaft, and the shaft being fixedlyattached at its ends to the frame. In the implement illustrated, thefront gang of plows is disposed at a slight angle with respect to theline of travel, and the rear gang is likewise disposed at a slightangle, but opposite to that of the front gang.

The steam delivery pipe 35 from the unit In extends horizontally andlongitudinally of the machine, and centrally over the two plow gangs andat points adjacent the gangs, has fittings 46 and 41 providingconnection respectively with cross headers 48 and 49 to supply them withsteam from pipe 35 for discharge into the ground within the furrowsformed by the disk plows.

4 It will be observed that each header, 48 and 49, is provided atintervals, corresponding to the spacing of the plow disks along theirmounting shafts, with fittings 55 whereby connection is made withdownwardly directed pipes 56 that extend along the back sides of thecorresponding disks and then turn rearwardly and each is connected witha horizontal pipe 58 which is designed to be drawn along the furrowformed by the corresponding plow disk and to be covered by the loosedirt thrown thereover by the action of the next adjacent disk. Thesehorizontal pipes are of such length that their rearward ends will, inoperation of the device, always be buried, and any steam that isdischarged therefrom must necessarily be retained in the soil.

The effectiveness of the present apparatus resides in the provision forcontrol of the expansion of steam from the point of initial generationthrough the superheating period and to the final point of application,and this is herein accomplished by the provision of distributing pipesof predetermined relationship and valves for the control of theadmittance of steam thereto.

The steam, as generated and confined in the boiler, can be released asdesired by the manipulation of hand valve 33, for admittance to thesuperheating coils. The superheated steam then flows through the pipe 35to the headers 48 and 49, for distribution to the pipes 56 and fordischarge from pipes 58. The headers are somewhat lesser in diameterthan pipe 35 and likewise the pipes 56 are of smaller diameter than theheaders so as to provide that all may be supplied to approximately thesame extent. However, the pipes 58 have a substantially greater diameterthan pipes 56.

The supply pipe 35 in an event would be sufficiently large to supply theheaders 48 and 49 with steam at substantially the same pressure asdelivered into pipe 35, and the pipes 55 which lead from the headerswould be reduced in size according to the number used so as to stillretain the pressure of the superheated steam. However, the pipes 58 inwhich the steam is permitted to expand should be substantially twice thediameter of the supply pipes 56.

In Figs. 5 and 6, I have illustrated an alternative piping arrangementwherein the steam delivery pipes 56' extend from the header, which maybe placed forwardly of the disks, horizontally and directly over thecross axle of the gang of plows; then directed downwardly and along therear faces of the plow disks, conforming to their contour, and connectat their lower ends, within the furrows provided by the plow disks, withthe horizontal, enlarged expansion sections 5811.

By reason of the pipes 58 or 58a. being substantially larger than thesupply pipes 55 and 55, the superheated steam supplied through thelatter will be given the opportunity of expanding to an appreciableextent so that it will not be discharged from the pipe 58 under anysubstantial degree of pressure that would blow the dirt back from theendof the discharge pipe. The pipe 58, however, retains the steamagainst dissipation of its heat until it is discharged into the ground.The loss of heat that is incident to the expansion of superheated steamin the pipe 58 is immaterial, and is not in the same proportion as wouldbe the case if saturated steam was admitted from pipe 56 into pipe 58.

It is understood that steam is admitted from the boiler as needed tosupply the system, under control of the valve 33.

Since the steam is emitted from the pipe 58 or 5811 under low pressure,which would be reduced to that pressure sufiicient only to cause it toenter the ground, and yet is admitted at high temperature, a veryeffective killing operation of seeds, insect eggs, larvae, etc., isaccomplished.

It is to be borne in mind that it is necessary to heat the ground to asubstantially high degree of temperature and this cannot be done to thedesired degree of satisfaction with the use of saturated steam, because,as soon as the saturated steam enters the ground, its expansiondecreases its temperature to a degree that is not sufiicient for theintended operation.

It is recognized that alterations, and modifications in the apparatusitself could be made without departing from the spirit of the invention,and therefore I do not desire that the claims be restricted to details,but that they be given and interpretation that is commensurate with theinvention disclosed.

Having thus described my invention, what I claim as new therein anddesire to secure by Letters Patent is- 1. A mobile apparatus forsterilizing soil comprising means for maintaining a supply ofsuperheated steam, means for turning furrows of soil, a pipe system forthe discharge of superheated steam from the supply into the groundbeneath the turned soil and including a section of pipe of increaseddiameter at the discharge end of the pipe system in which the steam willexpand and its pressure he reduced with no material loss of heat.

2. A mobile apparatus for sterilizing soil, comprising a means forgenerating steam, a superheating unit, means for efiecting a controlledadmittance of steam from the generator to the superheating unit, meansfor turning the soil in furrows, a piping system extending from thesuperheating unit forapplication of superheated steam to the soilbeneath the turned furrows of ground; said piping system having, at thedischarge end, a pipe section of increased diameter in which the steamwill expand with a resultant decrease in pressure with no substantialloss of heat.

3. An apparatus as recited in claim 2 wherein the pipe section ofincreased diameter is of substantial length and so disposed as to becontained lengthwis in the furrow formed by the soil turning means, andbeneath the turned soil.

BURR B. 'ELLIOTT.

